Aerosol dispensers have been in use for more than fifty years, and continue to gain in popularity because of the convenience of their use. However, many of those dispensers rely upon chemical propellants, including chloro-fluorocarbons and hydrocarbon compounds to pressurize the product. The use of chemical pressurizing agents creates special problems, including safety concerns in filling, shipping, handling, storing, using and disposing the pressurized, and often flammable containers. Another set of concerns involves questions relating to the effect of certain pressurizing chemical agents upon the earth's ecosystem, including on the ozone layer, and questions concerning the effect of the release of volatile organic compounds into the atmosphere. Accordingly, there has been great interest in the development of aerosol dispensers that do not use chemical propellants, but which also retain the conveniences of use associated with the chemically charged dispensers.
Among the alternatives to chemically pressurized aerosol dispensers are various mechanically pressurized models using finger pumps and triggers. These typically require a continued vigorous pumping to produce a continuous spray, and, as a result, are inconvenient to use. Further, the duration of the spray is in most instances limited by (1) the length of the stroke of the pump or trigger, (2) the fact that the pressure of the spray in most instances does not remain constant during a discharge cycle but decreases rapidly near the end of the cycle with the spray becoming a wet stream or dribble, and (3) the fact that the device must generally be operated in an upright position. In addition, many of the finger-operated pumps are not capable of producing a fine mist or suitably atomized spray for use with such products as cosmetics and hair sprays. As a result, such devices only partially solve the problem of providing a convenient, yet safe alternative to chemically pressurized aerosol dispensers.
Other alternatives to chemically pressurized dispensers include various mechanically pressurized models that obtain prolonged spray time by storing a charge without the use of chemical propellants. Such “stored charge” dispensers include types that are mechanically pressurized at the point of assembly, as well as types that may be mechanically pressurized by an operator at the time of use.
Stored charge dispensers that are pressurized at the point of assembly often include a bladder that is pumped up with product. Examples include those described in U.S. Pat. Nos. 4,387,833 and 4,423,829.
Stored charge dispensers that are pressurized by an operator at the time of use typically include charging chambers that are charged by way of screw threads, cams, levers, ratchets, gears, and other constructions providing a mechanical advantage for pressurizing a product contained within a chamber. This type of dispenser will be referred to as a “charging chamber dispenser.” Many ingenious charging dispensers have been produced. Examples include those described in U.S. Pat. No. 4,872,595 of Hammett et al., U.S. Pat. No. 4,222,500 of Capra et al., U.S. Pat. No. 4,174,052 of Capra et al., U.S. Pat. No. 4,167,941 of Capra et al., and U.S. Pat. No. 5,183,185 of Hutcheson et al., which is expressly incorporated by reference herein.
While some of the prior stored charge dispensers avoid some or all of the difficulties of the finger pump or trigger dispensers, the stored charge dispensers tend to have drawbacks of their own. In the devices pressurized at the point of assembly, the charging chamber is often an elastic bladder that remains charged during the life of the product, degrading over time, and these devices typically cannot be refilled with product. In the devices pressurized by an operator at the time of use, the charging chamber devices have been relatively difficult to manufacture due the large number of interrelated working parts required, and/or the fact that they are composed of parts not readily suited to high quantity, high yield injection molding production techniques, and/or the fact that they are required to be used with specially designed containers.
These drawbacks have tended to make the charging chamber dispensers expensive and not commercially feasible for mass market applications, and have tended to make other stored charge dispensers less than completely satisfactory substitutes for chemically pressurized dispensers. Accordingly, existing stored charge and charging chamber dispensers have only partially solved the problem of providing a convenient, yet safe alternative to chemically pressurized aerosol dispensers.
The current invention is a charging chamber dispenser that possesses specific improvements so that it combines convenience of use with commercial feasibility. It is believed that this is, finally, a non-chemical aerosol dispenser that retains the desirable features commonly associated with chemical aerosols, and is, therefore, a non-chemical aerosol dispenser that can attain widespread vendor and customer acceptance.